If you've used computers over the decades, you're probably aware the CPU chips have "multiple cores" and "graphics instructions" (or "SIMD instructions"). These first commonly turned up as new features in Intel's x86 chips in the late 90s and early 2000s.
But much less well known, is Apple computer - yes that Apple - was hard at work on a CPU chip with those features nearly a decade before. Work started in the mid 80s, and continued until the end of the decade. Now, obviously this project never saw the light of day. But some very smart technical people contributed to it, and from what I heard at the time the design was solid.
The CPU architecture was part of the "Aquarius project", a computer system based on the chip. The project was so secret it was conducted in a separate building in Cupertino, and only employees actually working on the project were allowed in.
This is one of the final design documents for the CPU. This copy was dated January 1989, probably within a year of the project's end.